Method of synchronizing a wireless device using an external clock

ABSTRACT

A method is provided for operating a dual-use wireless device. The method includes: receiving an external timing signal ( 460 ) at a first wireless circuit ( 480 ) in the device ( 605 ); synchronizing a first clock in the first wireless circuit with the external timing signal ( 610 ); sending a first internal timing signal ( 570 ) from the first wireless circuit to a second wireless circuit in the device, after the synchronizing ( 615 ); and listening for a remote periodic control signal at the second wireless circuit for a set monitoring time, a start of the monitoring time being based on the first internal timing signal ( 865 ). The second wireless circuit sends an association request if the second wireless circuit hears the remote periodic control signal within the monitoring time ( 875 ), and sends a local periodic control signal if the second wireless circuit does not hear the remote periodic control signal within the monitoring time ( 625 ).

FIELD OF THE INVENTION

The present invention relates in general to the operation of a wired orwireless network, and more particularly to a method of allowing awireless device to synchronize its operation using a clock signalexternal to the wireless device or any related wireless network.

BACKGROUND OF THE INVENTION

In ad hoc networking environments, networks can be created by differentdevices at different times, meaning that without receiving someinformation from the network, it is impossible for a new device todetermine what existing device is acting to coordinate a network, orexactly how the timing of the network is synchronized. The choice ofcoordinating device and the particular timing choices are made when anetwork first starts, and generally cannot be predicted withoutinformation from the network.

In a typical ad hoc networking environment, when a new device desires tocommunicate with other nearby devices, it will perform one of two tasks:joining an existing network, or creating a network of its own withitself as a network coordinator. In either case, however, this requiresfinding other devices that also desire to communicate with the newdevice. If joining an existing network, the new device will need to findthe device currently coordinating the existing network. If creating anew network, the device will need to find at least one other existingdevice desiring to join the new network and willing to accept the newdevice as a network coordinator. In both cases the new device will haveto synchronize its timing to that of the existing device.

When finding an existing network, the new device must first listen to adesired channel until it hears a signal identifying the existingnetwork, e.g., a periodic control signal that provides networkinformation. In one embodiment this identifying signal could be a beaconsignal from a network coordinator. Based on the new device's knowledgeof general network operation, the timing of the network identifyingsignal, and information contained in the network identifying signal, thenew device can then make an association request, asking to join theexisting network. The network coordinator of the existing network willprocess this association request and provide the new device withinstructions to join the network.

When starting a new network, the new device must generate its ownsignals identifying the new network, e.g., its own beacon signals, andwait to receive association requests from nearby devices desiring tojoin the new network. If the new device receives any such associationrequests, the new device can process them and accept nearby devices intothe new network.

However, any given device has no information regarding the identity ofany of the nearby devices, nor does it have any information as to howthe timing of any existing devices are set. As a result, a device tryingto identify the existence and timing of an existing network or devicewill have to listen for the device or network long enough to ensure thatit hears the proper synchronization information. This is at odds withpower saving modes that many devices have, which may have low dutycycles and long off-times.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures where like reference numerals refer toidentical or functionally similar elements and which together with thedetailed description below are incorporated in and form part of thespecification, serve to further illustrate an exemplary embodiment andto explain various principles and advantages in accordance with thepresent invention.

FIG. 1 is a block diagram of a wireless network according to a disclosedembodiment of the present invention;

FIG. 2 is a block diagram of a TDMA scheme including superframes,according to a disclosed embodiment of the present invention;

FIG. 3 is a block diagram of the timing for the creation of andassociation with networks according to a disclosed embodiment of thepresent invention;

FIG. 4 is a block diagram of two multiple-use ultrawide bandwidthdevices that operate in response to an external timing signal, accordingto a disclosed embodiment of the present invention;

FIG. 5 is a block diagram of the timing for the creation of andassociation with networks using an external timing signal, according toa disclosed embodiment of the present invention;

FIG. 6 is a block diagram of the timing for the creation of andassociation with networks using a monitoring window prior to sending abeacon, according to a disclosed embodiment of the present invention;

FIG. 7 is a flow chart of the operation of a network device acting as acoordinator according to a disclosed embodiment of the presentinvention;

FIG. 8 is a flow chart of the operation of a network device acting aseither a coordinator or a non-coordinator according to a disclosedembodiment of the present invention; and

FIG. 9 is a flow chart of the operation of a network device acting as anon-coordinating device according to a disclosed embodiment of thepresent invention.

DETAILED DESCRIPTION

The instant disclosure is provided to further explain in an enablingfashion the best modes of performing one or more embodiments of thepresent invention. The disclosure is further offered to enhance anunderstanding and appreciation for the inventive principles andadvantages thereof, rather than to limit in any manner the invention.The invention is defined solely by the appended claims including anyamendments made during the pendency of this application and allequivalents of those claims as issued.

It is further understood that the use of relational terms such as firstand second, and the like, if any, are used solely to distinguish onefrom another entity, item, or action without necessarily requiring orimplying any actual such relationship or order between such entities,items or actions. It is noted that some embodiments may include aplurality of processes or steps, which can be performed in any order,unless expressly and necessarily limited to a particular order; i.e.,processes or steps that are not so limited may be performed in anyorder.

Much of the inventive functionality and many of the inventive principleswhen implemented, are best supported with or in software or integratedcircuits (ICs), such as an embedded processor and software therefore orapplication specific ICs. It is expected that one of ordinary skill,notwithstanding possibly significant effort and many design choices-motivated by, for example, available time, current technology, andeconomic considerations, when guided by the concepts and principlesdisclosed herein will be readily capable of generating such softwareinstructions or ICs with minimal experimentation. Therefore, in theinterest of brevity and minimization of any risk of obscuring theprinciples and concepts according to the present invention, furtherdiscussion of such software and ICs, if any, will be limited to theessentials with respect to the principles and concepts used by theexemplary embodiments.

Wireless Network

FIG. 1 is a block diagram of a wireless network 100 according to adisclosed embodiment of the present invention. In this embodiment thenetwork 100 is a wireless personal area network (WPAN), or piconet.However, it should be understood that the present invention also appliesto other settings where bandwidth is to be shared among several users,such as, for example, wireless local area networks (WLAN), or any otherappropriate wired or wireless network.

When the term piconet is used, it refers to a wireless network ofdevices connected in an ad hoc fashion, having one device act as acoordinator (i.e., it functions as a master) while the other devices(sometimes called stations) follow the time allocation instructions ofthe coordinator (i.e., they function as slaves). The coordinator can bea designated device, or simply one of the devices chosen to function asa coordinator. One primary difference between the coordinator andnon-coordinator devices is that the coordinator must be able tocommunicate with all of the devices in the network, while the variousnon-coordinator devices need not be able to communicate with all of theother non-coordinator devices.

shown in FIG. 1, the network 100 includes a coordinator 110 and aplurality of devices 121-125. The coordinator 110 serves to control theoperation of the network 100. As noted above, the system of coordinator110 and devices 121-125 may be called a piconet, in which case thecoordinator 110 may be referred to as a piconet coordinator (PNC). Eachof the non-coordinator devices 121-125 must be connected to thecoordinator 110 via primary wireless links 130, and may also beconnected to one or more other non-coordinator devices 121-125 viasecondary wireless links 140, also called peer-to-peer links.

In addition, although FIG. 1 shows bi-directional links between devices,they could also be shown as unidirectional links. In this case, eachbi-directional link 130, 140 could be shown as two unidirectional links,the first going in one direction and the second going in the oppositedirection.

In some embodiments the coordinator 110 may be the same sort of deviceas any of the non-coordinator devices 121-125, except with theadditional functionality for coordinating the system, and therequirement that it communicates with every device 121-125 in thenetwork 100. In other embodiments the coordinator 110 may be a separatedesignated control unit that does not function as one of the devices121-125.

In some embodiments the coordinator 110 will be a device just like thenon-coordinator devices 121-125. In other embodiments the coordinator110 could be a separate device dedicated to that function. Furthermore,individual non-coordinator devices 121-125 could include the functionalelements of a coordinator 110, but not use them, functioning asnon-coordinator devices. This could be the case where any device is apotential coordinator 110, but only one actually serves that function ina given network.

Each device of the network 100 may be a different wireless device, forexample, a cellular telephone, a global positioning system (GPS) device,a digital still camera, a digital video camera, a personal dataassistant (PDA), a digital music player, a laptop personal computer, adesktop personal computer, or other personal wireless device.

The various non-coordinator devices 121-125 are confined to a usablephysical area 150, which is set based on the extent to which thecoordinator 110 can successfully communicate with each of thenon-coordinator devices 121-125. Any non-coordinator device 121-125 thatis able to communicate with the coordinator 110 (and vice versa) iswithin the usable area 150 of the network 100. As noted, however, it isnot necessary for every non-coordinator device 121-125 in the network100 to communicate with every other non-coordinator device 121-125.

Although a wireless network is described with reference to FIG. 1, andthe disclosure refers to this wireless network by way of example, thecurrent claimed invention is equally applicable to wired networks. Byway of example the present claimed invention could be applied towireless networks of the sort defined by the IEEE 802.11 standard or theIEEE 803.15.3 standard, the proposed IEEE 802.15.3b standard, by a wiredEthernet network, or to any other suitable wired or wireless network.

Superframes

The available bandwidth in a given network 100 may be split up in timeby the coordinator 110 into a series of repeated superframes. Thesesuperframes define how the available transmission time is split up amongvarious tasks. Individual frames of data are then transferred withinthese superframes in accordance with the timing set forth in thesuperframe.

FIG. 2 is a block diagram of a TDMA scheme including superframes andchannel time allocations according to a disclosed embodiment of thepresent invention. As shown in FIG. 2, the available transmission time200 is broken up into a plurality of consecutive superframes 210, eachsuperframe having a set superframe duration T_(SF).

The superframes 210 in this embodiment each include a superframe beacon220 during which beacon data is passed from a coordinator device to oneor more, and a superframe data portion 230 during which data is passed.The superframe beacon 220 has a beacon duration T_(SB); and thesuperframe data portion 230 has a superframe data portion durationT_(SD).

The superframe data portion 230 can be further divided into a contentionaccess period (CAP) 240, and a contention free period (CFP) 250. Thecontention free period 250 can then be further broken up into aplurality of channel time allocations (CTAs) 260 (also called timeslots).

The beacon period 220 is set aside for the coordinator 110 to send abeacon frame out to the non-coordinator devices 121-125 in the network100. Such a beacon frame will include information for organizing theoperation of devices within the superframe 210. Each non-coordinatordevice 121-125 knows how to recognize a beacon period 220 prior tojoining the network 100 so that it can identify the existing network 100and properly make an association request to join the network 100. Oncein the network 100, the non-coordinator device 121-125 uses the beacon220 both to coordinate communication within the network 100.

The beacon frame provides information required by the devices 121-125 inthe network 100 regarding how the individual channel time allocations260 will be allocated. In particular, it notes how and when devices 110,121-125 can transmit to prevent any two devices from interfering.

The CAP 240 is used to transmit commands or asynchronous data across thenetwork 100. In particular, the CAP 240 can be used in some embodimentsto provide a time for devices 121-125 outside of the network 100 to makeassociation requests to join the network 100. The CAP 240 may beeliminated in many embodiments and the system would then pass commandssolely during the CFP 250.

The CFP 250 includes a plurality of channel time allocations 260. Thesechannel time allocations 260 are each assigned by the coordinator 110 toone or more transmitting devices 110, 121-125 and one or more receivingdevices 110, 121-125 for transmission of information between them.Generally each transmitting device will have a single associatedreceiver, through in some cases a single transmitter will transmit tomultiple receivers at the same time. In embodiments without a CAP 240,certain CTAs 260 may be allocated for accepting association requests.

The channel time allocations 260 are provided to allow contention-freecommunication between devices 120, 121-125. They do so in accordancewith the information set forth in the beacon 220. The size of thechannel time allocations 260 can vary by embodiment, but it should belarge enough to transmit one or more data frames.

Although the embodiments described in this document are in the contextof a WPAN (or piconet), it should be understood that the presentinvention also applies to other settings where bandwidth is to be sharedamong several users, such as, for example, wireless local area networks(WLAN), other appropriate wireless network, or any wired or wirelesstransmission scheme in which bandwidth must be shared.

The superframes 210 are fixed time constructs that are generallyrepeated in time. The specific duration of the superframe 210 isdescribed in the beacon 220. In fact, the beacon 220 generally includesinformation regarding how often the beacon 220 is repeated, whicheffectively corresponds to the duration of the superframe 210. Thebeacon 220 also contains information regarding the network 100, such asthe identity of the transmitters and receivers assigned to each channeltime allocation 260, the necessary transmission parameters for signalswithin a channel time allocation 260, and the identity of thecoordinator 110.

The system clock for the network 100 is preferably synchronized throughthe generation and reception of the beacons 220 once devices 121-125 arein the network 100. Each non-coordinator device 121-125 will store asynchronization point time upon successful reception of a valid beacon220, and will then use this synchronization point time to adjust its owntiming.

Creation of Networks and Association of New Devices

Although FIG. 1 describes a network 100 with a coordinator 110 and aplurality of non-coordinator devices 121-125, at its inception, anetwork 100 can start with just two devices, one of which will take therole of coordinator 110, and one of which will take the role of anon-coordinator device 121-125.

Typically when a device begins operation it will look for an existingnetwork 100 to join. If it does not find a network 100 it may theneither go into a sleep mode for a time to save power, waking later toagain look for an existing network 100, or it may set itself as acoordinator 110, start its own network 100, send out a beacon 220, andbegin looking for other devices that may wish to join the network 100.

If no devices respond with an association request after one or morebeacons 220 have been sent, the new coordinator 110 might then enter asleep mode to save power. Having determined that there are no deviceswishing to join a network, the device will wait for a time and checkagain for nearby devices.

Because of the use of power-saving sleep modes, new devices, whetherlooking to join an existing network 100 or to start their own network100 may only spend a short time either looking for a network 100 orlooking for devices to join a network 100. The may actually spend alarger amount of time in a sleep mode to conserve power. As a result,two devices within range of each other might continually miss eachother, each being in a sleep mode when the other is in a waking mode andvice versa. Unless their monitoring processes were sufficientlyextensive, each would remain under the false impression that there wereno other devices within range. And extensive monitoring processesthemselves consume power. Thus, while long sleep times used by devicesduring sleep modes may improve power savings, the correspondingly longermonitoring processes required to look for adjacent devices will decreasepower savings.

FIG. 3 is a block .diagram of the timing for the creation of andassociation with networks 100 according to a disclosed embodiment of thepresent invention. FIG. 3 shows the timing for first, second, third, andfourth devices within a given locality. Each device begins being unawareof the existence of any other device. The first and the second devicesoperate as coordinator devices 110, attempting to start a new network100, inviting new devices to join. The third and fourth devices operateas non-coordinator devices 121-125, seeking an existing network 100 tojoin.

Consider the situation in which the first and the second devices arewithin range of each other. As shown in FIG. 3, the first device beginsby transmitting a beacon-1A 220A, defining a superframe-1A 210A. Thesuperframe-1A 220A will provide an opportunity in a data portion-1A 230Afor other devices that have heard the beacon-1A 220A to join a network100 using the first device as a coordinator 110. This opportunity couldcome in a CAP 240 or a CFP 250 in the data portion-1A 230A.

If no other device issues an association request to the first deviceduring the data portion-1A 230A, the first device will assume that thereare no devices in range that desire to join and will enter a sleep modefor a first device sleep period-A T_(S1A).

At the end of the first sleep period-A T_(S1A), the first device willtransmit a new beacon-1B 220B, defining a superframe-1B 210B. Thesuperframe-1B 220B will provide a new opportunity in a data portion-1B230B for other devices that have heard the beacon-1B 220B to join anetwork 100 using the first device as a coordinator 110.

Again, if no other device issues an association request to the firstdevice during the data portion-1B 230B, the first device will once moreassume that there are no devices in range that desire to join and willenter a sleep mode for a first device sleep period-B T_(S1B). The firstdevice sleep period-A T_(S1A) and the first device sleep period-BT_(S1B) may be the same or may vary in different embodiments.

This cycle of waking to send a beacon and then returning to a sleep modecan continue until either the device determines that it no longer wantsto create a network 100, it is shut off, or it finds another device andstarts a new network 100.

Similarly, the second device begins by transmitting a beacon-2A 320A,defining a superframe-2A 310A. The superframe-2A 320A will provide anopportunity in a data portion-2A 330A for other devices that have heardthe beacon-2A 320A to join a network 100 using the second device as acoordinator 110. This opportunity could come in a CAP 240 or a CFP 250in the data portion-2A 330A.

If no other device issues an association request to the second deviceduring the data portion-2A 330A, the second device will assume thatthere are no devices in range that desire to join and will enter a sleepmode for a second device sleep period-A T_(S2A).

At the end of the second device sleep period-A T_(S2A), the seconddevice will transmit a new beacon-2B 320B, defining a superframe-2B310B. The superframe-2B 320B will provide a new opportunity in a dataportion-2B 330B for other devices that have heard the beacon-2B 320B tojoin a network 100 using the second device as a coordinator 110.

Again, if no other device issues an association request to the seconddevice during the data portion-2B 330B, the second device will assumethat there are no devices in range that desire to join and will enter asleep mode, continuing this cycle of waking to send a beacon and thenreturning to a sleep mode until either the second device determines thatit no longer wants to create a network, it is shut off, or it findsanother device and starts the network.

Although FIG. 3 shows the first and second devices as each sending asingle beacon 220A, 320A, defining a single superframe respectively210A, 310A, before entering a sleep mode, this is by way of exampleonly. Each could send a series of superframes before entering a sleepmode. And the number of superframes sent between sleep cycles could varyor remain constant.

As shown in FIG. 3, it is entirely possible that the first and seconddevices will remain out of sync, i.e., the times the first device istransmitting a beacon 220A, 220B, are times when the second device isasleep, and vice versa, unless one scans the entire sleep interval tofind the other (as with the monitor window 350). Typically the beaconlength T_(SB) is on the order of about 100 μs, the superframe lengthT_(SF) is on the order of 10-65.5 ms, and the superframe sleep periodsT_(S1A), T_(S1B), T_(S2A) are on the order of hundreds of ms to severalseconds. This means that even if multiple beacons are broadcast in a rowbetween sleep periods, the times when a device is asleep will likely begreater than the time when the device is awake.

A similar situation will occur when one of the devices intends to becomea non-coordinator device 121-125 and is simply looking for an existingnetwork 100 to join. Consider the case where the first and third devicesare in operation within range of each other. The first device operatesas described above.

The third device will enter a waking mode for a set third monitor window340, having a third device listening period T_(L3), during which it willlisten for a beacon 220. If it hears a beacon 220 during the thirdmonitor window 340, it will send an association request during theproper time in the data portion 230 following the beacon 220. If it doesnot hear a beacon 220 during the third monitor window 340, it will enterinto a sleep mode for a third device sleep period T_(S3).

At the end of the third device sleep period TS₃, the third device willonce more enter a waking mode and again listen for a beacon 220. Thiscycle of waking to listen for a beacon 220 and then returning to a sleepmode can continue until either the third device determines that it nolonger wants to join a network, it is shut off, or it finds acoordinator 110 and joins that coordinator's network 100.

As shown in FIG. 3, it is entirely possible that the times the firstdevice is transmitting a beacon 220A, 220B, are times when the thirddevice is asleep, and the times that the third device is listening aretimes when the first device is asleep. As a result, both the firstdevice and the third device might be completely unaware of the other,despite the fact that they are actually looking for each other.

As noted above, typically the beacon length T_(SB) is on the order ofabout 100 μs, the superframe length T_(SF) is on the order of 10-65.5ms, and the first and second device sleep periods T_(S1A), T_(S1B),T_(S2A) are on the order of hundreds of ms to several seconds. Inaddition, the third device sleep period T_(S3) is also typically on theorder of hundreds of ms to several seconds. This means that even ifmultiple beacons 220 are broadcast in a row between sleep periods, thetimes when a device is asleep will likely be greater than the time whenthe device is awake.

The only way a listening (i.e., non-coordinator) device can be certainto hear any beacons 220 that are being broadcast is to have the lengthof its monitor window be longer by two beacon lengths than the longestpossible sleep period in a network 100 it's listening for.

Consider the case of a fourth device designed to ensure that it willhear a transmitted beacon 220. The fourth device will enter a wakingmode for a set fourth monitor window 350, having a fourth devicelistening period T_(L4), during which it will listen for a beacon 220.If it hears a beacon 220 during the monitor window 340, it will send anassociation request during the proper time in the data portion 230following the beacon 220. If it does not hear a beacon 220 during thefourth monitor window 350, it will enter into a sleep mode in a mannersimilar to that described for the third device.

Unlike the third device, however, the fourth device has the length ofits monitor window 350 set to guarantee that it will hear any beaconsbeing broadcast. Assuming for the sake of argument that the first devicesleep period-A T_(S1A) is the longest possible sleep period for thefirst device, this means that the fourth device listening period T_(L4)must be equal to:T _(L4)=2*(T _(SB))+T _(S1A)  (1)

Given this listening period T_(L4), the fourth device is guaranteed thatno matter when it starts listening, it will hear a beacon if anotherdevice in range is broadcasting one. However, the cost for thisguarantee is that the fourth device must remain in a listening mode fora comparatively long time, which can cause a significant power drain inthe fourth device in a situation in which there is no guarantee thatthere is even another device nearby. This can be particularlydetrimental if the fourth device is powered by a battery.

External Timing Signals

Some wireless devices are dual-use devices, meaning they are capable oftwo different types of wireless connection. For example they may becapable of a long-range wireless connection, e.g., cellular telephonecommunications, global positioning system (GPS) signal monitoring, NISTclock signal monitoring, TV clock signal monitoring, or the like, aswell as a short-range wireless connection, e.g., a WPAN or WLANconnection using wideband or ultrawide bandwidth (UWB) connections. Insome of these dual-use devices, one of the wireless functions mayinvolve the use of an external timing signal. For example, cellulartelephone systems generally employ an external timing signal tosynchronize the operation of the cell phone network. Likewise, a GPSsystem will employ an external clocking signal to coordinate theprocessing of its global positioning signals. There are also broadcastclock signals such as those used in some television broadcasts to allowvideo recorders and the like to synchronize their timing, or thosebroadcast by NIST or others to help clocks synchronize their timing.

Often these external timing signals will be continuously monitored by afirst wireless circuit in the dual-use device during the device'soperation. In such a case, a second wireless circuit in the dual-usedevice can use this external timing signal received by the firstwireless circuit as a time reference to help coordinate the timing ofthe second wireless circuit.

FIG. 4 is a block diagram of two dual-use wireless devices with portionsthat operate in response to an external timing signal, according to adisclosed embodiment of the present invention. As shown in FIG. 4, twodevices 110, 121-125 are provided, along with an external timing device450. Each of the devices 110, 121-125 contains an antenna 470, a firstwireless circuit 480, a second wireless circuit 490, and a coordinationcircuit 495.

The antenna 470 is used for the device 110, 121-125 to send and receivewireless signals to and from the first wireless circuit 480 and thesecond wireless circuit 490. It may be a single antenna that servicesboth wireless circuits 480 and 490, or it may be two separate antennas,e.g., one UWB antenna and one cellular telephone antenna. In a wiredembodiment, the antenna 470 could be replaced with a connection to aninput/output wire.

The first wireless circuit 480 sends and receives signals in a firstformat from the antenna 470, operating in a known fashion. In variousembodiments the second wireless circuit 490 could be a cellulartelephone circuit, a GPS circuit, NIST clock signals, television clocksignals, or the like. These signals include an external timing signal460 received from an external timing device 450.

The second wireless circuit 490 sends and receives wireless signals in asecond format from the antenna 470, operating in a known fashion. Thesecould be RF signals, wideband signals, UWB signals, or the like. By wayof example, a UWB circuit will be described below as the first wirelesscircuit. However, it should be understood that this is by way ofexample, and should not limit the second wireless circuit 490 in anyway.

In this exemplary embodiment, the second wireless circuits 490 in thetwo devices 110, 121-125 communicate with each other via primary orsecondary wireless links 130 or 140. If one of the devices is acoordinator device 110, then they communicate via a primary wirelesslink 130; if both of the devices are non-coordinator devices 121-125,then they communicate via a secondary wireless link 140.

The coordination circuit 495 facilitates communication between the firstwireless circuit 480 and the second wireless circuit 490. It mayphysically associate with one of the first wireless circuit 480 or thesecond wireless circuit 490, or it may be a physically separate circuit.

The external timing device 450 provides the external timing signal 460to each of the devices 110, 121-125. This external timing signal 460 isused by the first wireless circuit 480 in normal operation. In oneembodiment the external timing device 470 is a central cellulartelephone station and the external timing signal 460 is a cellulartelephone clock signal; in another embodiment external timing device 470is a GPS satellite and the external timing signal 460 is a GPS timingsignal. Other embodiments can use different devices as an externaltiming device 480.

In each device 110, 121-125, the first wireless circuit 480 and thefirst wireless circuit 480 communicate with each other through thecoordination circuit 495. In particular, the first wireless circuit 480can inform the second wireless circuit 490 that an external timingsignal 460 has been received. This will allow the second wirelesscircuit 490 in each device 110, 121-125 to synchronize with the externaltiming signal 460, despite the fact that their respective first wirelesscircuits 480 may not have been synchronized with respect to each other.

Use of an External Timing Signal to Coordinate Sending Beacons

FIG. 5 is a block diagram of the timing for the creation of andassociation with networks using an external timing signal, according toa disclosed embodiment of the present invention. This embodiment uses aUWB circuit as the first wireless circuit, but this is by way of exampleonly. The timing of FIG. 5 shows the operation of an external timingdevice 450, a second wireless circuit 490 in a first device acting as anetwork coordinator 110, and a second wireless circuit 490 in a seconddevice acting as a non-coordinator device 121-125. FIG. 6 is a flowchart of the operation of a network device acting as a coordinatoraccording to a disclosed embodiment of the present invention.

In the system shown in FIGS. 5 and 6, the first device is attempting tocreate a wireless network 100 (i.e., a UWB network in this example), andis looking for other devices to join. The second device is looking tojoin an existing wireless network 100. The first and second devices aredual-use devices, containing both a first wireless circuit 480 (e.g., acellular telephone circuit) and a second wireless circuit 490 (e.g., aUWB circuit), as described with respect to FIG. 4. In addition, thesecond wireless circuits 490 in both the first and the second devicesare capable of entering a sleep mode to conserve power.

As shown in FIG. 5, an external timing device 450 periodically transmitsan external timing signal 460, with a known time between external timingsignals 460. This time between external timing signals may be fixed ormay vary, but should be predictable to the dual-use devices.

A first wireless circuit 480 in the first device receives the externaltiming signal 460 (605) and synchronizes its second clock to thereceived timing signal. (610).

The first wireless circuit 480 in the first device then provides a firstinternal timing signal to the second wireless circuit 490 in the firstdevice based on the second clock. (615). This first internal timingsignal could be a timing signal that directly instructs the secondwireless circuit 490 to take some action, or it could be used by thesecond wireless circuit 490 for synchronization of its own second clock.In the latter case, the second wireless circuit 490 synchronizes itssecond clock to the timing information from the first wireless circuit480 (and thus to the external timing signal, to which the first clock issynchronized) and generates its own second internal timing signal. (620)

Regardless, the first device produces an internal timing signal 570 thatis generated a known time T_(K) after the transmission by the externaltiming device 450 of an external timing signal 460. The second wirelesscircuit 490 in the first device can use the internal timing signal 570(whether a first internal timing signal received from the first wirelesscircuit 480 or second internal timing signal generated within the secondwireless circuit 490), to set the time for broadcasting a beacon.

The second wireless circuit 490 in the first device uses the internaltiming signal (first or second, as appropriate to the embodiment) as atrigger to send out a first beacon 220A, defining a first superframe210A. (625) Following the transmission of the first beacon 220A, thesecond wireless circuit 490 listens during an appropriate time duringthe first data portion 230A, in the first superframe 210A, for anyresponse to the first beacon 220A, e.g., an association request from anearby device. (630)

If the second wireless circuit 490 in the first device does receive anassociation request during the first data portion 230A (635), it willprocess that response and continue network operation. (640) If thesecond wireless circuit 490 in the first device does not receive anassociation request during the first data portion 230A (635), it willenter a sleep mode for a first sleep period T_(S1). (645) In oneembodiment in which the second wireless circuit 490 is a UWB circuit, atypical association wait time is in the range of 10 to 200 microseconds.

The length of the first sleep period T_(S1) will be set based on thegaps between internal timing signals 570. In particular the first sleepperiod T_(S1) will be the time between two internal timing signals 570.These may be adjacent internal timing signals 570, or they may beinternal timing signals 570 separated by one or more other internaltiming signals 570. Whichever of the first wireless circuit 480 or thesecond wireless circuit 490 in the first device that generate theinternal timing signal 570 can be tasked to mark the time accordingly todetermine when the internal timing signal 570 corresponding to the endof the sleep period is received or should be generated (depending uponthe particular embodiment).

Thus, in an embodiment in which the second wireless circuit 490 does notsynchronize its first clock to the external timing signal 460, the firstwireless circuit 480 in the first device will determine when the firstsleep period T_(S1) has elapsed and will send a (first) internal timingsignal 570 to the second wireless circuit 490 in the first deviceindicating that the first sleep period T_(S1) has elapsed. (650)

Similarly, in an embodiment in which the second wireless circuit 490does synchronize its first clock to the external timing signal 460, thesecond wireless circuit 490 in the first device will determine when thefirst sleep period T_(S1), has elapsed and generate a (second) internaltiming signal 570 indicating this fact. (655)

The second wireless circuit 490 in the first device then uses theinternal timing signal 570 (whether first or second) as a trigger toexit the sleep mode (660) and to send out a second beacon 220B, defininga second superframe 210B. (625) Following the transmission of the secondbeacon 220B, the second wireless circuit 490 in the first device listensduring an appropriate time during a second data portion 230B for anyassociation request from a nearby device. (630)

If the second wireless circuit 490 in the first device does receive anassociation request during the second data portion 230B (635), it willprocess that association request and continue network operation to allowa new device to join the network 100. (640) If the second wirelesscircuit 490 in the first device does not receive an association requestduring the second data portion 230B (635), it will again enter a sleepmode (645), repeating this process until either it successfully receivesan association request, it receives instructions to stop looking for newdevices, or it is shut off.

In this way, the dual use device can schedule the timing of the beacons(or more generally any periodic control signal) relative to the timingof the external timing signal 460 by synchronizing the timing of theinternal timing signal 570 to that of the external timing signal 460.Each dual-use device will synchronize its own internal timing signal 570to this known, global external timing signal 460. The particulars of howthe internal timing signals 570 are generated (e.g., frequency, period,etc.) and how a beacon 220 (or other periodic control signal) is sentbased on the internal timing signals 570 will be known to each device(either in a first or second wireless circuit 480 or 490). Once theirinternal timing signals 570 are all synchronized to the same externaltiming signal 460, each device will know when beacons 220 (or otherperiodic control signals) are being sent.

Although this method discloses a single synchronizing event with theexternal timing signal, the receipt of the external timing signal 460can be performed periodically to maintain proper synchronization betweenthe external timing signal 460 and the first clock in the first wirelesscircuit 480. And if the second wireless circuit 490 also synchronizesits second clock to the external timing signal 460, this synchronizationcan likewise be periodically repeated throughout operation.

In addition, although not shown, this process may provide other ways toexit the processing loop 600. For example, the second wireless circuit490 in the first device might monitor the number of times a beacon 220is sent out and exit the loop 600 if a certain number of beacons 220pass without response.

Use of a Delay after an External Timing Signal to Avoid BeaconCollisions

Because the second wireless circuits in the wireless devices (i.e., UWBdevices in the disclosed embodiment) are synchronizing with the sameexternal timing signal 460, two or more would-be network coordinators110 might transmit a beacon at exactly the same time, i.e., a known timeT_(K) after a first wireless circuit 480 receives of an external timingsignal 460. This could cause the beacons 220 to collide, making neitherof them readable to any device listening. And since each would-becoordinator 110 would be transmitting, not listening, neither of thecolliding devices would be able to hear the other. In order to avoidsuch collisions, a delay can be used in some embodiments between when adual-use wireless device receives an external timing signal 460 and whenthe first wireless circuit in that device broadcasts a beacon to try andcreate a new network 100.

This delay can be random or set in some predictable fashion such asbeing chosen from a predetermined set of possible delay times. But itshould provide for the likelihood that individual would-be networkcoordinators 110 will likely delay a different amount of time from whenthey receive the external clocking signal 460. This delay can vary fromzero up to a maximum delay amount. In one embodiment in which the secondwireless circuit is a UWB circuit, this delay can vary between 10microseconds to 100 milliseconds.

Furthermore, because each would-be network coordinator 110 could alsooperate as a non-coordinator 121-125, a given device can use this delayperiod as a monitor window for the second wireless circuit 490 to listento a second wireless channel for a beacon 220 from another would-becoordinator 110. If the second wireless circuit 490 in the currentdevice hears another beacon 220 during this monitor window, it canrequest to join that network rather than trying to start its own. And ifthe delay time is determined such that multiple adjacent devices areunlikely to choose the same delay time, then the use of such a delaywill reduce the chance of a collision between two beacons transmitted bysecond wireless circuits 490 in two or more adjacent devices.

FIG. 7 is a block diagram of the timing for the creation of andassociation with networks using a monitoring window prior to sending abeacon, according to a disclosed embodiment of the present invention.FIG. 8 is a flow chart of the operation of a dual-use wireless device inwhich its second wireless circuits act as either a coordinator or anon-coordinator according to a disclosed embodiment of the presentinvention.

As shown in FIGS. 7 and 8, the first wireless circuit 480 in a dual-usedevice that would act as coordinator receives an external timing signal460 from an external timing device 450 (605), and synchronizes its firstclock to the external timing signal 460. (610)

The first wireless circuit 480 then provides a first internal timingsignal to the second wireless circuit 490 based on its first clock.(615). This could be an internal timing signal that directly instructsthe second wireless circuit 490 to take some action, or it could be usedby the second wireless circuit 490 for synchronization of its own secondclock. In the latter case, the second wireless circuit 490 synchronizesits second clock to the first internal timing signal from the firstwireless circuit 480 (and thus to the external timing signal, to whichthe second clock is synchronized) and generates its own second internaltiming signal. (620)

Regardless, the first device produces an internal timing signal 570 thatis generated a known time T_(K) after the transmission by the externaltiming device 450 of an external timing signal 460. The internal timingsignal 570 could be a first internal timing signal generated by thefirst wireless circuit 480 or a second internal timing signal generatedby the second wireless circuit 490. However for ease of description, itis referred to in FIG. 7 as an internal clock signal 570, regardless ofits origin.

In response to the internal timing signal 570, either received from thefirst wireless circuit 480 (i.e., the first internal timing signal) orgenerated by the second wireless circuit 490 (i.e., the second internaltiming signal), the second wireless circuit 490 enters into a monitorwindow period 740 during which it listens for a beacon 220 for avariable wait time T_(V). (865) If the wait time T_(V) happens to bezero, the monitor window 740 can be eliminated, and the process becomesas described with respect to FIG. 6.

If during the monitor window 740 the second wireless circuit 490receives a beacon 220 (870) then it will make an association requestbased on the information in that beacon 220, and continue normal networkoperations as a non-coordinator device 121-125 in another network 100.(875)

If, however, the second wireless circuit 490 does not receive a beacon220 during the monitor window 640 (870) then it will broadcast a beacon220 (625) and listen for a response to the beacon 220, e.g., anassociation request. (630)

If the second wireless circuit 490 determines that a response, e.g., anassociation request, has been received (635) within an appropriate partof the data portion 230 after the beacon 220, then it processes theresponse and proceeds with normal network operation. (640) If, however,the second wireless circuit 490 determines that a response has not beenreceived (635), it then enters into a sleep mode. (645)

The length of the sleep period that the second wireless circuit 490remains in the sleep mode will be set based on the gaps between internaltiming signals 570. In particular the sleep period will be the timebetween two internal timing signals 570. These may be adjacent internaltiming signals 570, or they may be internal timing signals 570 separatedby one or more other internal timing signals 570. Whichever of the firstwireless circuit 480 or the second wireless circuit 490 in the firstdevice that generate the internal timing signal 570 can be tasked tomark the time accordingly to determine when the internal timing signal570 corresponding to the end of the sleep period is received or shouldbe generated (depending upon the particular embodiment).

Thus, in an embodiment in which the second wireless circuit 490 does notsynchronize its second clock to the external timing signal 460, thefirst wireless circuit 480 in the first device will determine when thesleep period has elapsed and will send an internal timing signal 570 tothe second wireless circuit 490 in the first device indicating that thesleep period has elapsed. (650)

Similarly, in an embodiment in which the second wireless circuit 490does synchronize its second clock to the external timing signal 460, thesecond wireless circuit 490 in the first device will determine when thesleep period has elapsed and generate an internal timing signal 570indicating this fact. (655)

The second wireless circuit 490 in the first device then uses theinternal timing signal 570 as a trigger to exit the sleep mode (660) andagain enter a monitor window 740 to listen for a beacon for a variableamount of time T_(V). (865) The variable time T_(V) may remain constantonce set for each operation of this process 800, or it may change eachtime the second wireless circuit 490 begins a new monitor window 740.(865)

As with the process 600 of FIG. 6, the monitoring of the number oftiming signals received in the process 800 may be performed by eitherthe first wireless circuit 480 or the second wireless circuit 490. Also,as in the process 600 of FIG. 6, this process 800 may provide other waysto exit the processing loop 800.

Use of an External Timing Signal to Coordinate Listening for Beacons

In the system shown in FIGS. 5 and 9, a second wireless circuit 490 in asecond device is attempting to find and join an existing wirelessnetwork 100. The second device is a dual-use device, containing both afirst wireless circuit 480 and a second wireless circuit 490, asdescribed with respect to FIG. 4. As with the first device describedwith respect to FIGS. 5 and 6, the second wireless circuit 490 in thesecond device is a UWB device, though this can change in alternateembodiments.

FIG. 9 is a flow chart of the operation of a network device acting as anon-coordinating device 121-125 according to a disclosed embodiment ofthe present invention.

As shown in FIGS. 5 and 9, a first wireless circuit 480 in the seconddevice receives the external timing signal 460 (905) and synchronizesits first clock to the received timing signal. (910).

The first wireless circuit 480 in the second device then provides afirst internal timing signal to the second wireless circuit 490 in thesecond device based on the first clock. (915). This could be a timingsignal that directly instructs the second wireless circuit 490 to takesome action, or it could be used by the second wireless circuit 490 forsynchronization of its own second clock. In the latter case, the secondwireless circuit 490 synchronizes its second clock to the first internaltiming signal from the first wireless circuit 480 (and thus to theexternal timing signal, to which the first clock is synchronized) andgenerates its own second internal timing signal. (920)

Regardless, the second device produces an internal timing signal 570that is generated a known time T_(K) after the transmission by theexternal timing device 450 of an external timing signal 460. The secondwireless circuit 490 in the second device can use the internal timingsignal 570 (whether a first internal timing signal received from thefirst wireless circuit 480 or second internal timing signal generatedwithin the second wireless circuit 490), to set the time for listeningfor a broadcast a beacon.

The second wireless circuit 490 in the second device uses the internaltiming signal 570 as a trigger to start listening for a beacon 220 for aset monitor window 540. (930) Although shown as being the same size asthe beacons 220A, 220B, the monitor window 540 can be larger, e.g., toaccount for delays in the first device broadcasting a beacon 220.Regardless, it should be of sufficient size to allow enough time afterthe external timing signal 460 for the second wireless circuit 490 inthe second device to hear any beacon 220 that is being transmitted, evenif a maximum allowable delay is employed by a coordinator device 10between receiving the external timing signal 460 and broadcasting abeacon 220.

If the second wireless circuit 490 in the second device does hear abeacon 220 during the monitor window 540 (935), it will send anassociation request at an appropriate time and format in response to thereceived beacon 220 and then proceed with normal network operation as anon-coordinator device 121-125 in the network 100. (940)

If, however, the second wireless circuit 490 in the second devicedetermines that no beacon 220 has been received by the end of themonitor window 540 (935) then it enters into a sleep mode for a secondsleep period T_(S2). (945)

The length of the second sleep period T_(S2) will be set based on thegaps between internal timing signals 570. In particular the second sleepperiod T_(S2) will be the time between two internal timing signals 570.These may be adjacent internal timing signals 570, or they may beinternal timing signals 570 separated by one or more other internaltiming signals 570. Whichever of the first wireless circuit 480 or thesecond wireless circuit 490 in the second device that generates theinternal timing signal 570 can be tasked to mark the time accordingly todetermine when the internal timing signal 570 corresponding to the endof the second sleep period T_(S2) is received or should be generated(depending upon the particular embodiment).

Thus, in an embodiment in which the second wireless circuit 490 in thesecond device does not synchronize its second clock to the externaltiming signal 460, the first wireless circuit 480 in the second devicewill determine when the second sleep period T_(S2) has elapsed and willsend an internal timing signal 570 to the second wireless circuit 490 inthe second device indicating that the second sleep period T_(S2) haselapsed. (950)

Similarly, in an embodiment in which the second wireless circuit 490 inthe second device does synchronize its second clock to the externaltiming signal 460, the second wireless circuit 490 in the second devicewill determine when the second sleep period T_(S2) has elapsed andgenerate an internal timing signal 570 indicating this fact. (955)

The second wireless circuit 490 in the second UWB device uses theinternal timing signal as a trigger to exit the sleep mode (960) and tobegin another monitor window period 540 in which is listens for a beacon220. (930)

If the second wireless circuit 490 in the second device does hear abeacon 220 during this new monitor window 540 (935), it will make anassociation request at the appropriate time and continue operation as anon-coordinator device 121-125 in the new network 100. (940) If thesecond wireless circuit 490 in the second device does not hear a beacon220 within the monitor window (935), it will again enter sleep mode(945), repeating this process until either it hears a beacon 220 andsuccessfully joins a network 100, it receives instructions to stoplooking, or it is shut off.

Because the second wireless circuits 490 in the first and second devicesare coordinating their sleep modes and waking modes based on an externaltiming signal 460 that each of their corresponding first wirelesscircuits hear, the length of a required monitor window 540 issignificantly reduced. The second wireless circuits 490 in the firstdevice will always send out a beacon 220A, 220B a known time T_(K) afterreceipt of an external timing signal 460. The second wireless circuits490 in the second device need only listen for a monitor window 540 atthis same time, the monitor window 540 being long enough to make certainany beacon 220A, 220B is heard. After this time the second device willknow that no beacons will be transmitted and so can safely enter a sleepmode until the proper amount of time has passed for the next beacon 220to be sent. Since the first and second devices are both synchronized tothe external timing signal 460, they will be able to calculate thissleep time in the same way to get the same result.

Although FIG. 5 shows that the second wireless circuit 490 in the firstdevice only sends a single beacon 220A prior to entering a sleep mode(i.e., for the first sleep period T_(S1)), in alternate embodiments itcould send multiple beacons 220, defining multiple superframes 210,prior to entering a sleep mode.

Furthermore, although FIG. 5 shows that the first and second beacons220A, 220B are sent immediately after receipt of the internal timingsignal 570, there will actually be a processing delay between receivingthe internal timing signal 570 and sending a beacon 220A, 220B. Thisaccounts for circuit delays to process the internal timing signal 570,which may be greater if the first wireless circuit 480 in a dual-usedevice generates the internal timing signal 570 to control operation ofthe second wireless circuit 490. However, for ease of disclosure, thefirst and second beacons 220A, 220B are shown as being generated rightafter the external timing signal 460.

Also, although FIG. 5 shows only two devices operating in a given area,multiple devices could be operating at the same time. This means thatmultiple non-coordinator devices 121-125 could be listening for beacons220 at the same time, and multiple would-be network coordinators 110could be sending out beacons 220 at the same time.

This process may also provide other ways to exit the processing loop900. For example, the second wireless circuit 490 in a the second devicemight monitor the number of times the device enters a monitor window540, and exit the loop 900 if a certain number of monitor windows 540pass without detecting a beacon 220.

This monitoring process can also be used by non-coordinator devices121-125 in the embodiment of FIGS. 7 and 8. In this case, any devicedesiring simply to become a non-coordinator device and join an existingnetwork should set its own monitor window 540 to be long enough toaccount for the length of a beacon 220 plus the longest possiblevariable wait time T_(v). This way even if there is only a single devicetransmitting a beacon 220 and it chooses the maximum variable wait timeT_(v), the monitor window 540 of the non-coordinator device 121-125 willstill be long enough for the device to hear the beacon 220.

Conclusion

This disclosure is intended to explain how to fashion and use variousembodiments in accordance with the invention rather than to limit thetrue, intended, and fair scope and spirit thereof. The foregoingdescription is not intended to be exhaustive or to limit the inventionto the precise form disclosed. Modifications or variations are possiblein light of the above teachings. The embodiment(s) was chosen anddescribed to provide the best illustration of the principles of theinvention and its practical application, and to enable one of ordinaryskill in the art to utilize the invention in various embodiments andwith various modifications as are suited to the particular usecontemplated. All such modifications and variations are within the scopeof the invention as determined by the appended claims, as may be amendedduring the pendency of this application for patent, and all equivalentsthereof, when interpreted in accordance with the breadth to which theyare fairly, legally, and equitably entitled. The various circuitsdescribed above can be implemented in discrete circuits or integratedcircuits, as desired by implementation.

1. A method of transmitting a periodic control signal in a dual-usewireless device, comprising: receiving an external timing signal at afirst wireless circuit in the dual-use wireless device; synchronizing afirst clock in the first wireless circuit with the external timingsignal; sending a first internal timing signal from the first wirelesscircuit to a second wireless circuit in the dual-use wireless device,after synchronizing the first clock with the external timing signal; andbroadcasting the periodic control signal at the second wireless circuitbased on the first internal timing signal.
 2. A method of transmitting aperiodic control signal, as recited in claim 1, further comprisingwaiting a delay time between sending the first internal timing signaland broadcasting the periodic control signal.
 3. A method oftransmitting a periodic control frame, as recited in claim 2, whereinthe delay time is one of: randomly determined, or iteratively chosenfrom a predetermined set of possible delay times.
 4. A method oftransmitting a periodic control signal, as recited in claim 1, furthercomprising: synchronizing a second clock in the second wireless circuitwith the first internal timing signal; and generating a second internaltiming signal in the second wireless circuit, after synchronizing thesecond clock with the first internal timing signal, wherein the periodiccontrol signal is broadcast in response to the second internal timingsignal.
 5. A method of transmitting a periodic control signal, asrecited in claim 4, further comprising waiting a delay time betweensending the second internal timing signal and broadcasting the periodiccontrol signal.
 6. A method of transmitting a periodic control frame, asrecited in claim 5, wherein the delay time is one of: randomlydetermined, or iteratively chosen from a predetermined set of possibledelay times.
 7. A method of transmitting a periodic control signal, asrecited in claim 1, wherein the external timing signal is one of aglobal positioning system signal, a cell phone timing signal, atelevision clock signal, and a broadcast clock signal.
 8. A method oftransmitting a periodic control signal, as recited in claim 1, furthercomprising: listening for an association request at the second wirelesscircuit for an association wait time after broadcasting the periodiccontrol signal; performing an association function if the associationrequest is received within the association wait time; and entering intoa sleep mode if the association request is not received within a theassociation wait time.
 9. A method of transmitting a periodic controlsignal, as recited in claim 1, wherein the second wireless circuit is anultrawide bandwidth circuit.
 10. A method of transmitting a periodiccontrol signal, as recited in claim 1, wherein the method is implementedin an integrated circuit.
 11. A method of operating a dual-use wirelessdevice, comprising: receiving an external timing signal at a firstwireless circuit in the dual-use wireless device; synchronizing a firstclock in the first wireless circuit with the external timing signal;sending a first internal timing signal from the first wireless circuitto a second wireless circuit in the dual-use wireless device, aftersynchronizing the first clock with the external timing signal; andlistening for a remote periodic control signal at the second wirelesscircuit in the dual-use device for a set monitoring time, a start timeof the set monitoring time being based on the first internal timingsignal.
 12. A method of operating a dual-use wireless device, as recitedin claim 11, wherein the timing signal is one of a global positioningsystem signal, a cell phone timing signal, a television clock signal,and a broadcast clock signal.
 13. A method of operating a dual-usewireless device, as recited in claim 11, further comprising: sending anassociation request from the second wireless circuit if the secondwireless circuit hears the remote periodic control signal within themonitoring time; sending a local periodic control signal from the secondwireless circuit if the second wireless circuit does not hear the remoteperiodic control signal within the monitoring time.
 14. A method ofoperating a dual-use wireless device, as recited in claim 13, furthercomprising: listening at the second wireless circuit for an associationrequest for an association wait time after sending the local periodiccontrol signal; performing an association function if the associationrequest is received within the association wait time; and entering intoa sleep mode if the association request is not received within a theassociation wait time.
 15. A method of operating a dual-use wirelessdevice, as recited in claim 11, wherein the second wireless circuit isan ultrawide bandwidth circuit.
 16. A method of operating a dual-usewireless device, as recited in claim 11, wherein the method isimplemented in an integrated circuit.
 17. A dual-use wirelesscommunication device, comprising: a first wireless circuit for receivingfirst wireless signals, including an external timing signal; a secondwireless circuit for receiving second wireless signals; and acoordination circuit connected between the first wireless circuit andthe second wireless circuit for providing an internal timing signal tothe second wireless circuit, the internal timing signal being generatedin response to the external timing signal.
 18. A wireless communicationdevice, as recited in claim 17, wherein the first wireless circuit isone of a cellular telephone circuit, a global positioning systemreceiver, a television receiver, and a broadcast clock receiver.
 19. Awireless communication device, as recited in claim 17, wherein thesecond wireless circuit is an ultrawide bandwidth circuit.
 20. Awireless communication device, as recited in claim 17, wherein thesecond wireless circuit is implemented on an integrated circuit.